v.1.1 Since we have in fact already said that one must choose the mean, and not the excess or the deficiency, and since the mean is as correct reasoning says it is, let us make some distinctions here. In all the states discussed, just as in other matters, there is a target which the rational person looks to as he intensifies and relaxes, and there is a defining limit for the mean states, which we say lie between the excess and the deficiency, being in accordance with correct reasoning. v.1.2 Now this claim is true, but not at all clear. For in other concerns governed by knowledge it is true to say that one ought to labour and to ease off neither too much nor too little, but moderately and as correct reasoning indicates. But assuming that this is all one has, one would be none the wiser about how to treat the body if one were to say ‘what medicine and the medical practitioner dictates’. v.1.3 That is why when it comes to the states of the soul this claim, though true, is not enough, but there must also be distinctions about what the correct reasoning is and what its defining limit is.
v.1.4 When we distinguished the virtues of the soul we said that some were virtues of character and some virtues of thought. We have dealt with the virtues of character; let us now discuss the others, after first saying something about the soul. v.1.5 Earlier, then, it was said that there are two parts of the soul, one rational and the other non-rational. Now we should make a similar division with regard to the rational part, and let it be postulated that there are two rational parts, one by which we contemplate the kinds of existing things whose starting points cannot be otherwise and the other by which we contemplate things which admit of being otherwise. For corresponding to objects which differ in kind there are also parts of the soul, different in kind, which naturally correspond to each kind of object, if it really is the case that they have knowledge in accordance with a kind of similarity and suitability. v.1.6 Let one of these be called ‘scientific’ and the other ‘calculative’; deliberation and calculation are the same and no one deliberates about things which do not admit of being otherwise. Consequently, the calculative is a single, distinct part of the rational part. v.1.7 One should, then, get a grasp of what the best state of each of these rational parts is. For this is the virtue of each and the virtue is relative to its proper function.